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Unformatted text preview: Harvard-MIT Division of Health Sciences and Technology HST.542J: Quantitative Physiology: Organ Transport Systems Instructors: Roger Mark and Jose Venegas MASSACHUSETTS INSTITUTE OF TECHNOLOGY Departments of Electrical Engineering, Mechanical Engineering, and the Harvard-MIT Division of Health Sciences and Technology 6.022J/2.792J/BEH.371J/HST542J: Quantitative Physiology: Organ Transport Systems PROBLEM SET 9 SOLUTIONS April 23, 2004 Problem 1 Emphysema is one of the leading causes of death in the United States. Our ability to treat emphy- sema is severely limited because the principal physiologic deficiency results from the destruction of the architecture of the lung. The development of lung transplantation was the first direct ap- proach to the treatment of advanced emphysema. However, most patients with severe disease are precluded from undergoing this surgery by advanced age and coexisting conditions. Lung-reduction surgery is the newest therapeutic option for patients with emphysema and one that is potentially available to many more patients. The idea of removing 25 percent or more of the lung from a patient with marginal lung function appears, to say the least, counterintuitive. Nevertheless, in certain patients with emphysema, lung-reduction surgery can result in substantial lessening of dyspnea and improved overall function and quality of life for up to a year after surgery. A. First, draw the normal chest wall and lung compliance curves. Then, draw the changes that result from emphysema, which increases compliance of the lungs. Assume that the chest wall doesn’t change. What happens to FRC with emphysema? B. Second, draw the effects of removing 25 percent of lung tissue. What happens to the amount of pressure and work required to inspire a similar tidal volume? In emphysema, the increase in compliance leads to a steeper lung compliance curve, and FRC will increase. This leads the respiratory system to function on the high part of the pressure-volume curve, which requires more work to inspire a given tidal volume, even though lung compliance has increased. Removing 25 The emphysematous destruction of lung tissue causes a loss of elastic recoil. This loss of...
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This note was uploaded on 11/11/2011 for the course BIO 2.797j taught by Professor Matthewlang during the Fall '06 term at MIT.
- Fall '06